Filler assembly for cable gland

ABSTRACT

A dispenser apparatus ( 2 ) for a curable liquid material is disclosed. The apparatus comprises a flexible bag ( 8 ) defining a first compartment ( 10 ) for accommodating a first component of a curable liquid material, and a second compartment ( 12 ) for accommodating a second component of the curable liquid material and adapted to communicate with the first chamber to enable mixing of the first and second components to initiate curing of the curable liquid material. A first clamp ( 14 ) temporarily prevents mixing of the first and second components, and an elongate nozzle ( 16 ) communicates with the second compartment to dispense the mixed curable liquid material therefrom. A second clamp ( 18 ) temporarily prevents passage of the curable liquid material from the second compartment to the nozzle.

The present invention relates to a filler assembly for cable glands andrelates particularly, but not exclusively, to such a filler assembly forfilling cable glands for use in hazardous areas.

Many cable glands for use in connecting a cable to an enclosure inhazardous areas need to be filled with a compound which provides abarrier against the effects of an explosion occurring within theenclosure to which the cable gland is attached. The barrier is typicallyformed from a two-part clay-filled epoxy compound. The two componentparts of the compound need to be thoroughly mixed with each other priorto fitting into the gland, and the resulting putty like material needsto be packed between the individual conductors in the cable. Such anarrangement is disclosed in GB 2258350.

This known arrangement suffers from a number of drawbacks. Firstly, thecure time of the putty like material is chosen to be relatively long, inorder to enable it to be manipulated into the spaces between theindividual conductors before curing becomes advanced. As a result, thefilled cable assembly must be left undisturbed for a significant period,usually several hours, especially if mixed at low temperatures. Also,the components of the filler material sometimes contain hazardousmaterials which become harmless when the filler material is mixed.Persons mixing the components of the putty like filler material may comeinto contact with these hazardous materials during mixing, and air canbecome trapped within the cable gland by the filler material which maycause the barrier formed by the filler material to fail in the event ofan explosion. Filling of the cable gland is also relatively difficult,especially in the case of small cable glands.

GB 765082 discloses an arrangement for insulating a splice between twostranded connectors in which resinous material is introduced from acapsule having an elongate tip. However, this arrangement suffers fromthe drawback that it is not suitable for filling cable glands, since theintroduction of a material which is sufficiently fluid to penetratebetween the individual conductors of a cable would cause material toflow along the conductors along the interior of the cable, which wouldprevent the cable gland from being sufficiently filled to expel all ofthe air from the cable gland to avoid air voids.

Preferred embodiments of the present invention seek to overcome one ormore of the above disadvantages of the prior art.

According to an aspect of the present invention, there is provided afiller assembly for filling a cable gland, having a plurality of coresof at least one cable extending therethrough, with curable liquidmaterial, the assembly comprising:

(a) a dispenser apparatus for a curable liquid material, the apparatuscomprising:

a body adapted to define at least one first chamber for accommodating afirst component of a curable liquid material and at least one secondchamber for accommodating a second component of said curable liquidmaterial and adapted to communicate with at least one said first chamberto enable mixing of said first and second components to initiate curingof said curable liquid material;

first barrier means for temporarily preventing mixing of said first andsecond components;

elongate dispenser means adapted to communicate with at least one saidsecond chamber and to dispense said mixed curable liquid materialtherefrom between a plurality of cores of at least one cable; and

second barrier means for temporarily preventing passage of said curableliquid material from the or each said second chamber to said dispensermeans; and

(b) at least one barrier member for restricting the extent ofpenetration of said curable liquid material along said cores.

By providing elongate dispenser means to dispense mixed curable liquidmaterial and second barrier means for temporarily preventing passage ofthe curable liquid material to said dispenser means, this provides theadvantage that the first and second components of the curable liquidmaterial can be mixed in a sealed container comprising the first andsecond compartments, thus enabling the user to avoid coming into contactwith harmful components of the curable liquid material. As a result ofthe provision of elongate dispenser means, dispensing of the curableliquid can be more carefully controlled, as a result of which lessviscous and faster curing liquid material can be used than in the priorart. This therefore provides the advantage of enabling more rapidformation of a filled cable gland incorporating the material, while alsoallowing the liquid material to be introduced into the cable gland insuch a way that the air is expelled from the cable gland to avoid airvoids, which could lead to failure of the cable gland in the event of anexplosion. In addition, with the present invention, the curable materialcan be dispensed into the assembled gland, i.e. the cable gland can befilled with the conductors of the cable in a connected state, as aresult of which the electrical integrity of the joint can be ensured,whereas the putty like compound of the known arrangement must be mouldedaround the conductors of the cable with the gland disassembled, as aresult of which the cable cores can not be electrically connected. Theprovision of at least one barrier member for restricting the extent ofpenetration of said curable liquid material along the cable coresprovides the advantage of enabling highly flowable curable liquidmaterial to be used, while also enabling filling of the cable gland.

The body may be flexible.

This provides the advantage of making the apparatus easier and lessexpensive to manufacture.

The first and/or second barrier means may comprise at least onereleasable clamp.

The assembly may further comprise a first component of a curable liquidmaterial in at least one said first chamber, and a second component ofsaid curable liquid material in at least one said second chamber.

The curable liquid material may be adapted to change colour as a resultof curing thereof.

This provides the advantage of providing a visual indicator to the userwhen the cable gland filling process is complete.

The assembly may further comprise a cover member for covering anexternal screw thread of a cable gland to prevent said curable liquidmaterial coming into contact with said screw thread.

The cover member may be adapted to prevent curable liquid material frompenetrating an end face of the cable gland.

At least one said barrier member may comprise a respective flexiblemember having at least one aperture therethrough for engaging at leastone core of at least one cable.

At least one said barrier member may have a respective tapering portion.

According to another aspect of the present invention, there is provideda method of filling a cable gland with curable liquid material by meansof an assembly according to any one of the preceding claims, the methodcomprising:

locating at least one said barrier member in the cable gland; and

locating an outlet of said dispenser means in said cable gland anddispensing curable liquid material therefrom so as to expel air from thecable gland.

The step of locating at least one said barrier member in the cable glandmay comprise locating at least one said barrier member around at leastone said core of at least one said cable.

A preferred embodiment of the invention will now be described, by way ofexample only and not in any limitative sense, with reference to theaccompanying drawings in which:

FIG. 1 is a perspective view of a dispensing apparatus embodying thepresent invention;

FIG. 2 is a partially cut away perspective view of a cable gland havinga filler formed using the apparatus of FIG. 1; and

FIG. 3 is a cross sectional view of the filled cable gland of FIG. 2with a thread protector in place.

Referring to FIG. 1, a dispenser apparatus 2 embodying the presentinvention and for use in filling a cable gland 4 (FIG. 2) with curableliquid material 6 comprises a body of suitable transparent flexibleplastics material defining a flexible bag 8 having a first compartment10 for accommodating a first component of a liquid curable material 6,and a second compartment 12 for accommodating a second component of thematerial 6. A first clamp 14 temporarily separates the first compartment10 and second compartment 12 to thereby prevent mixing of the first andsecond components of the material 6. The first and second components arecoloured differently (for example blue and yellow) so that thoroughmixing of the first and second components produces a green liquid,thereby providing a visual indication when thorough mixing of the firstand second components has occurred. Mixing of the first and secondcomponents together causes gelling of the material and initiates curingof the curable liquid material 6.

The dispenser apparatus 2 is also provided with an elongate hollownozzle 16 extending from the second compartment 12 such that dispensingof the mixed curable liquid material can be carefully controlled. Inparticular, the nozzle 16 can be inserted a considerable distance intothe cable gland 4 and between individual conductors 20 of the core of acable 22 attached to the cable gland 4 (FIG. 2) so that the liquidmaterial 6 can be highly flowable and fast-curing, as a result of whichthe cable gland 4 can be rapidly filled and air entrapment by the liquidmaterial 6 minimised. A second clamp 18 temporarily prevents materialflowing from the second compartment 12 into the nozzle 16, so thatdispensing of the material 6 can be prevented until thorough mixingtogether of the first and second components has occurred.

The flexible bag 8 is formed from two sheets of material welded togetheralong all but one of their edges to form a bag having an open mouth,which is then mounted to the nozzle 16. The second clamp 18 is thenmounted to the bag adjacent to the nozzle 16, and the second componentof the material 6 is dispensed into the second compartment 12. The firstclamp 14 is then mounted to the bag to seal the second component in thesecond compartment 12, and the first component is then dispensed intothe first compartment 10. The open edge of the bag is then sealed toseal the first component in the first compartment 10.

Referring to FIGS. 2 and 3, the cable gland 4 to be filled by means ofthe dispenser apparatus 2 of FIG. 1 comprises a threaded outer connector24 for threaded connection to an enclosure (not shown) and a compoundtube 26 rotatably mounted within the outer connector 24. A cableconnector 28 is mounted to the end of the cable 22 and is connected tothe outer connector 24 by means of cooperating screw threads (notshown).

A ring 30 abuts the cable connector 28 and a flexible seal 32 is locatedaround the inner conductors 20 of the cable 22 and compressed betweenthe compound tube 26 and ring 30 for limiting the extent of penetrationof curable material 6 into the cable gland 4 before curing of thecurable material 6. The flexible seal 32 comprises a generallyfrusto-conical body of elastomeric material having an aperture (notshown) therethrough for engaging the central conductors 20 of the cable22. The aperture in the seal 32 is sized such that it stretches to passaround the conductors 20 to tightly engage the conductors 20 to form areasonably effective barrier to passage of the material 6 along thespace defined between the conductors 20 and the compound tube 26.

Referring to FIG. 3, a thread protector 34 formed of elastomericmaterial such as rubber is located over the external screw thread of theouter connector 24 of the cable gland 4 prior to filling of the cablegland with curable material 6. The thread protector 34 has a hollow rim36 for catching excess curable material 6 which may flow out of end 40of the cable gland 4 during the filling procedure, and an inner circularrim 38 which prevents penetration of curable material 6 into the gapbetween the outer connector 24 and the compound tube 26. This ensuresthat the compound tube 24 complete with cable connectors 20 can beremoved from the outer connector 24 after curing of the material 6.

The process of filling the cable gland 4 of FIGS. 2 and 3 by means ofthe dispenser apparatus 2 of FIG. 1 will now be described.

In order to fill the core of the cable gland 4 with curable material,the flexible seal 32 initially placed over the core conductors 20 of thecable 22 so that the seal 32 tightly grips the conductors 20. The outerconnector 24 with compound tube 26 are then mounted to the ring 30 andcable connector 28 to compress the seal 32 between the ring 30 andcompound tube 26. As a result, the flexible seal 32 acts as a barrier topenetration of the curable liquid material 6 into the interior of thecable gland 4.

The first clamp 14 is then removed from the dispenser apparatus 2 andthe second clamp 18 left in place, to enable thorough mixing of thefirst and second components of the curable liquid material 6. The firstand second components are coloured blue and yellow respectively, aresult of which the curable liquid material 6 is bright green when it isthoroughly mixed. The second clamp 18 is then removed, and the outlet ofthe nozzle 16 is placed at a location near the seal 32. The liquidmaterial 6 is then dispensed through the nozzle 16 into the spacebetween the conductors 20 of the cable 22 and into the space around theconductors 20 inside the compound tube 26 of the cable gland 4, whereits movement along the axis of the cable gland 4 is restricted by theflexible seal 32. The location of the outlet of the nozzle 16 near theseal 32 causes air to be expelled from the cable gland when the curableliquid material 6 is dispensed from the nozzle 16. The seal 32 providesa sufficient barrier to penetration of the material 6 to hold back thecurable material until it begins to gel and support itself. At the sametime, the thread protector 34 protects the external thread of the outerconnector 24 from excess curable material and prevents penetration ofthe liquid curable material between the outer connector 24 and thecompound tube 26. The material 6 is arranged to change colour to darkgreen when it is cured, so that a visual indication is provided when thecuring process is completed.

It will be appreciated by persons skilled in the art that the aboveembodiment has been described by way of example only, and not in anylimitative sense, and that various alterations and modifications arepossible without departure from the scope of the invention as defined bythe appended claims.

1. A filler assembly for filling a cable gland, having a plurality ofcores of at least one cable extending therethrough, with curable liquidmaterial, the assembly comprising: (a) a dispenser apparatus for acurable liquid material, the apparatus comprising: a body adapted todefine at least one first chamber for accommodating a first component ofa curable liquid material, and at least one second chamber foraccommodating a second component of said curable liquid material andadapted to communicate with at least one said first chamber to enablemixing of said first and second components to initiate curing of saidcurable liquid material; at least one first barrier apparatus fortemporarily preventing mixing of said first and second components; atleast one elongate dispenser apparatus adapted to communicate with atleast one said second chamber and to dispense said mixed curable liquidmaterial therefrom between a plurality of cores of at least one cable;and at least one second barrier apparatus for temporarily preventingpassage of said curable liquid material from the or each said secondchamber to at least one said dispenser apparatus; and (b) at least onebarrier member for restricting the extent of penetration of said curableliquid material along said cores.
 2. An assembly according to claim 1,wherein said body is flexible.
 3. An assembly according to claim 1,wherein at least one said first barrier apparatus comprises at least onereleasable clamp.
 4. An assembly according to claim 1, furthercomprising a first component of a curable liquid material in at leastone said first chamber, and a second component of said curable liquidmaterial in at least one said second chamber.
 5. An assembly accordingto claim 5, wherein the curable liquid material is adapted to changecolor as a result of curing thereof.
 6. An assembly according to claim1, further comprising a cover member for covering an external screwthread of a cable gland to prevent said curable liquid material cominginto contact with said screw thread.
 7. An assembly according to claim6, wherein the cover member is adapted to prevent curable liquidmaterial from penetrating an end face of the cable gland.
 8. An assemblyaccording to claim 1, wherein at least one said barrier member comprisesa respective flexible member having at least one aperture therethroughfor engaging at least one core of at least one cable.
 9. An assemblyaccording to claim 1, wherein at least one said barrier member has arespective tapering portion.
 10. A method of filling a cable gland withcurable liquid material by means of an assembly according to claim 1,the method comprising: locating at least one said barrier member in thecable gland; and locating an outlet of at least one said dispenserapparatus in said cable gland and dispensing curable liquid materialtherefrom so as to expel air from the cable gland.
 11. A methodaccording to claim 10, wherein the step of locating at least one saidbarrier member in the cable gland comprises locating at least one saidbarrier member around at least one said core of at least one said cable.12. An assembly according to claim 1, wherein at least one said secondbarrier apparatus comprises at least one releasable clamp.